Burner with flame shaping means



P 1959 J. w. DOLBY 2,905,235

BURNER WITH FLAME SHAPING MEANS Filed April l2, 1956 IN V EN TOR.

a//in W D016 United Stat 2,905,235 Patented Sept. 22, 1959 2,905,235- BURNER WITH FLAME SHAPING MEANS John W. Dolby, Elgin, Ill., assignor to Configured Tube Products Company, Bellwood, 11]., a corporation of Illinois Application April 12, 1956, Serial No. 577,761

3 Claims. (Cl. 158-113) This invention relates to burners for gaseous fuel, such as natural gas, manufactured gas, and so-called bottled gas derived from liquified petroleum gases.

One principal object of the present invention is to provide a new and improved burner adapted to produce a flame of a particular, desired shape, such as a thin, flat shape.

A further object is to provide a new and improved burner adapted to produce a flame that will fit into a heat exchanger of desired shape, particularly a flat oblong shape.

It is another object to provide a new and improved burner of the foregoing character which employs a mixing tube of circular cross section and with a single circular exit port, together with means for shaping the burner flame so that it will be flat and oblong in cross section.

A further object is to provide such a new and improved burner which is capable of producing an efficient, smokeless flame.

Another object is to provide such a new and improved burner that will produce 'an extremely heat output.

Still another object is to provide such a new and improved burner which is so arranged that the flame will not be likely to flash back through the mixing tube.

Further objects and advantages of the present invention will appear from the following description, taken with the accompanying drawings, in which:

Fig. l is a side elevational view of an illustrative embodiment of the invention in the form of a burner for gaseous fuel.

Fig. 2 is :an elevational sectional view of the portion of the burner adapted to receive the fuel and air.

Fig. 3 is an end elevational view looking toward the right hand or exit end of the burner shown in Fig. 1.

Fig. 4 is a horizontal sectional view of the exit end of the burner, taken generally along a line 4-4 in Fig. 1.

As already indicated, Fig. 1 illustrates a burner adapted to utilize gaseous fuel, such as natural gas, manufactured gas, or liquified petroleum gas, for example. The burner 10 may be employed for various purposes. For example, the burner 10 has been found to be very advantageous for use as a source of heat in household clothes dryers. In such dryers, the burner is employed to heat air which in turn is utilized to dry the clothes.

Such a dryer or the like may include a heat exchanger which defines a chamber for the burner flame. The mechanical design of various household clothes dryers may make it advantageous to form the heat exchanger with this chamber in various shapes. For example, the heat exchanger may be formed with a fairly flat or narrow flame chamber which is oblong in cross. section. The illustrated burner 10 may be employed very advantageously in connection with such a heat exchanger, because the illustrated burner is adapted to produce a flat, wide flame that will fit into such a flat, oblong flame chamber. Tailoring the shape of the flame to fit into the heat exchanger in this manner makes it possible to run the burner with maximum heat output, without danger that the flame will generate an objectionable amount of carbon monoxide.

It will be seen that the illustrated burner 10 comprises a mixing tube 12 of circular cross section. The illus trated mixing tube 12 has an entrance portion 14 adapted to receive fuel and air. In this instance the entrance portion 14 is cylindrical in shape.

At its opposite end, the mixing tube 12 is formed with an exit portion 16 which terminates in a single, circular exit port 18 adapted to discharge a stream of mixed fuel and air. A venturi throat portion 20 is interposed be tween the entrance and exit portions 14 and 16 of the mixing tube 12.

Gaseous fuel is introduced into the entrance portion 14 by a nozzle 22 connected to a supply pipe or conduit 24. It will be seen that the nozzle 22 has an orifice 26 that is disposed axially in the entrance portion or housing 14 and is directed toward the axis of the venturi throat 20.

Air is admitted to the entrance housing 14 by suitable openings therein, such as the illustrated pair of circular openings 28 on opposite sides of the entrance housing 14. A cylindrical shutter 30 is adjustably mounted around the entrance housing 14 to regulate the flow of air through the openings 28. The shutter 30 may be rotated through a suitable range, such as degrees, for example, and may be locked in its adjusted position by means of a clamping screw 32 tapped into the housing 14 and extending through a peripheral slot 34 formed in the shutter 30. It wlll be seen that the shutter 30 is formed with a pair of circular openings 36 adapted to be registered in varying degrees with the openings 28 in the entrance housing 14 The exit portion 16 of the mixing tube 12 is generally of slightly flaring form, but is curved inwardly at its extreme end to define an inturned annular flange 38 disposed around the exit port 18. This curved flange 38 tends to focus or narrow the flame by directing the mixed fuel and air toward the axis of the port 18.

In accordance with the present invention, the burner 10 is provided with flame shaping means, such as the illustrated target 40. As shown, the target 40 comprises a pair of spaced vertical bars 42 which extend transversely to the length of the mixing tube 12 and are spaced outwardly beyond the exit port 18. It will be seen that the bars 42 are interposed in the path of the stream of fuel and air discharged by the port 18. An oblong, rectangular open space 44 is formed between the bars 42 and is aligned with the axis of the port 18. Thus, the bars 42 deflect the stream of fuel and air so that the main portion of the stream passes through the open space 44 between the bars 42 in a flat oblong form, as indicated by the arrows 46 in Fig. 4.

It is preferred that the target bars 42 be flat and oblong in cross section and be arranged with inner flat surfaces 48 facing generally toward the exit port 18, but extending at angles lying between the transverse and longitudinal directions. It will be seen that the left and right hand bars 42 are oppositely angled so as to be symmetrical about a vertical plane extending through the axis of the port 18. Starting from their outer edges, the bars 42 angle away from the port 18 so that the inner surfaces 48 will deflect the stream of fuel and air through the rectangular opening 44 between the bars 42. As illustrated, the flat surfaces 48 make an acute angle with the transverse direction. The actual angle of the bars 42 may vary, but is shown as about 30 degrees to the transverse direction.

To support the bars 42, the target 40 is formed with a pair of supporting arms 50 which are welded or otherwise secured at their inner ends to the mixing tube 12. It will be seen that the arms 50 extend longitudinally beyond 3 the outer end of the mixing tube and are connected to the ends of the bars 42. In this instance, the bars 42 and the arms 50 are formed integrally out of sheet metal. The mixing tube 12 and the shutter 30 are also preferably made out of sheet metal.

It will be seen from Fig. 4 that the supporting arms 50 are provided with two forked portions 52 which support the bars 42. Thus, the supporting arms 50 are generally Y-shaped as viewed broadside.

In the operation of the burner, the nozzle 22 directs gaseous fuel through the entrance housing 14 and into the venturi portion 20. The action of the venturi portion 20 draws air into the mixing tube 12 through the openings 28 and 36 in the housing 14 and the shutter 30. The gas and air are mixed in the mixing tube 12 and are discharged in a stream from the single exit port 18.

The main portion of the stream from the exit port 18 passes through the oblong opening 44 between the bars 42, of the target 40. This portion of the stream of fuel and air forms the main portion of the burner flame. The flame has its base immediately in front of the target bars 42. Thus, the target 40 has the effect of displacing the base of the flame outwardly from the exit port 18. The main portion of the flame is flat and oblong in cross section. A focusing effect is produced by theppposite angling of the target bars 42. The flatness of the flame is due to a considerable extent to this focusing effect. The shape of the flame is also due to a considerable extent to the oblong shape of the opening between the bars 42.

Small side flames are produced adjacent the base of the main flame by portions of the stream of fuel and air which are deflected outwardly by the bars 42, as indicated by the arrows 54 in Fig. 4. The disposition and angling of the bars 42 is such that the edge portions of the stream of fuel and air are deflected outwardly, as indicated by these arrows, instead of passing through the opening 44 between the bars 42. Some of the fuel and air pass between the forks 52 of the supporting arms 50 so as to feed these side flames.

The side flames have an important stabilizing effect upon the main portion of the burner flame. The provision of the side flames tends to prevent the main portion of the flame from being blown outwardly, away from the target bars 42, by secondary air drawn into the base of the flame.

In addition to forming the flame into a flat, oblong shape, the target 40 has the effect of preventing the flame from flashing back through the mixing tube 12. Thus, the target 40 increases the effective depth of the single exit port 18. The provision of the target greatly stabilizes the burner flame and permits operation at high rates of fuel flow without trouble from the flames flashing back or blowing out.

In shaping the flame, the target acts in cooperation with the curved flange around the exit port. This cooperative action also contributes to the ability of the burner to prevent the flame from flashing back into the mixing tube.

The burner is effective and stable in operation, yet is reasonably easy to manufacture and low in cost. The burner provides a flat, wide flame that will fit into oblong heat exchangers. High heat output may be obtained from the burner without causing instability of the flame or producing objectionable amounts of carbon monoxide.

Various modifications, alternative constructions and equivalents may be employed without departing from the true spirit and scope of the invention as exemplified in the foregoing description and defined in the following claims:

I claim:

1. In a burner for gaseous fuel, the combination comprising a fuel-air mixing tube having an entrance portion, an exit portion, and a venturi throat portion therebetween, means for directing fuel axially into said entrance portion toward said venturi throat portion, means for admitting air into said entrance portion for mixing with the fuel, said exit portion terminating in a single axial exit port therein for discharging a stream of fuel and air, said exit portion curving inwardly around said port to define an inturned annular flange therearound, a flame shaping target made of sheet metal and having a pair of supporting arms mounted on said exit portion at diametrically opposite points and extending longitudinally therefrom beyond said flange and said port in spaced generally parallel relation, a pair of flat narrow bar portions extending between said arms transversely thereto and spaced outwardly from said port in the path of the stream of fuel and air therefrom, said bar portions being spaced apart laterally and having inner lateral edges defining a rectangular open space therebetween disposed axially of said port, said bar portions being flat throughout their extent and being spaced apart from each other a distance substantially less than the diameter of said port to overlap said port and intercept the mixture discharged therefrom, said bar portions having outer lateral edges opposite said inner edges and spaced outwardly from said tube to define lateral openings between said tube and said bar portions, the distance between said outer lateral edges of said bar portions being generally equal to but slightly greater than the diameter of said port so that said bar portions will deflect a portion of the mixture laterally, said bar portions having flat surfaces facing generally toward said port but inclined oppositely at angles between transverse and longitudinal directions, said angles being acute with respect to the transverse direction.

2. In a burner for gaseous fuel, the combination comprising a fuel-air mixing tube, means for discharging a stream of fuel into one end of said mixing tube and directed, toward the opposite end thereof, means for ad,- mitting air to said one end of said mixing tube, said tube having a single exit port at said opposite end thereof for discharging a stream of fuel and air therefrom, said mixing tube having a smoothly curved annular inturned flange thereon around said exit port, a flame-shaping target mounted on said tube and having a pair of supporting arms extending longitudinally therefrom beyond said opposite end thereof, a pair of spaced generally parallel bars extending between said arms transversely thereto and spaced in front of said exit port in the path of the stream of fuel and air therefrom, said bars being oblong in cross section and having flat sides extending at an angle between the transverse and the longitudinal, said angle being acute with respect to the transverse, each of said bars having generally parallel inner and outer lateral edges, said inner lateral edges of said bars being spaced apart from and generally parallel to each other to define a generally rectangular opening therebetween disposed axially of said tube, said outer lateral edges being spaced outwardly from said tube to define lateral openings therebetween, said bars being flat throughout their extent and being spaced apart from each other a distance substantially less than the diameter of said port to overlap said port and intercept the mixture discharged therefrom, the distance between said outer lateral edges of said bars being generally equal to but slightly greater than the diameter of said port so that said bars will deflect a portion of the mixture laterally.

3. In a burner for gaseous fuel, the combination comprising a fuel-air mixing tube having an entrance portion, an exit portion, and a venturi throat portion therebetween, means for directing fuel axially into said entrance portion toward said venturi throat portion, means for admitting air into said entrance portion for mixing with the fuel, said exit portion terminating in a single axial exit port therein for discharging a stream of fuel and air, a flame shaping target having a pair of supporting arms mounted on said exit portion at diametrically opposite points and extending longitudinally therefrom beyond said port in spaced generally parallel relation, a pair of flat bar portions extending between said arms transversely thereto and spaced outwardly from said port in the path of the stream of fuel and air therefrom, said bar portions being spaced apart laterally and having inner lateral edges defining a rectangular open space therebetween disposed axially of said port, said bar portions being flat throughout their extent and being spaced apart from each other a distance substantially less than the diameter of said port to overlap said port and intercept the mixture discharged therefrom, said bar portions having outer lateral edges opposite said inner edges and spaced outwardly from said tube to define lateral openings between said tube and said bar portions, the distance between said outer lateral edges of said bar portions being generally equal to but slightly greater than the diameter of said port so that said 1 bar portions will deflect a portion of the mixture laterally,

References Cited in the file of this patent UNITED STATES PATENTS 73,957 Darling Feb. 4, 1868 617,200 Strauss Jan. 3, 1899 1,097,825 Steele May 26, 1914 1,775,866 Salz Sept. 16, 1930 2,542,335 Kapit et a1. Feb. 20, 1951 2,731,009 Pocrass et al Jan. 17, 1956 FOREIGN PATENTS 772,290 France Aug. 13, 1934 

